Wirkungen von zeitlich begrenzten Stickstoff- und Cytokiningaben auf die Fahnenblatt- und Kornentwicklung von Weizen

Effects of temporary applications of nitrogen and cytokinins on the development of flag leaf and grain growth in wheat Influence of nitrogen and cytokinin treatments (N, Cy) restricted to the ‘early’ and ‘late’ grain filling period on different developmental processes was examined in two spring wheats grown in hydroculture under nutritional conditions that were nearly optimal for the overall-development. (1) As to the flag leaf, additional early N-supply raised maximum chlorophyll content only slightly, but as late applications strongly delayed pigment destruction and loss of green area. Corresponding treatments with Cy were effective in the same way, but to a lesser degree. The higher efficiency of late applications of N or Cy indicated their limiting function during senescence. (2) Early treatments which increased number of kernels in parts of the ear showed that endogenous N- or Cy-levels were not sufficient for grain setting. Grain growth was stimulated only by early Cy-applications in exp. II in which Cy had no effect on kernel number, whereas late treatments were generally ineffective. Different N-levels in plants obviously did not limit grain growth, but high ones favoured tillering which presumably prevented increase of yield. (3) The genotypes, Solo and Kolibri, although opposite in their character, showed comparable responses to treatments with slight differents only in the extent of the reaction.     

Wurzelstudien und Phosphat-Aufnahme von Weidelgras und Rotklee unter Feldbedingungen

Root studies and phosphorus uptake of rye-grass and red clover under field conditions Root parameters (fresh weight, density, surface, length, cation exchange capacity) and phosphate uptake were studied with rye grass and red clover, grown in the field on a brown podsolic soil. In all root parameters, ry grass was superior to red clover. Also, phosphate uptake of rye grass was higher than that of red clover. The greatest difference between both species was found in root length, that of rye grass being about five times longer than that of red clover. Rye grass had longer root hairs than red clover; whereas root diameter of clover was about twice as thick the average rye grass. Significant correlations were observed between root parameters and phosphate uptake in the plants studied. The highest correlation coefficients were obtained for the relationship P-uptake versus root length (clover 0.91***, grass 0.87***) and P-uptake versus root fresh weight (clover 0.92***, grass 0.88***). The phosphate uptake per unit root parameters was significantly higher in red clover, compared with rye grass, for the parameters root fresh weight, cation exchange capacity and root length. Because of this high P-uptake rate for clover it is assumed that clover also requires a higher P-concentration in soil solution as compared with grass. Thus grass may still grow with low P concentrations in the soil solution without P deficiency at which clover cannot grow. It is for this reason that in mixed swards clover is depressed by grass, if the available P in the soil is low.     

Einfluß von Stickstoff- und Cytokiningaben auf die Entwicklung des Fahnenblattes und der Karyopsen von Weizen

Influence of nitrogen and cytokinin applications on the development of flag leaves and grains of wheat In two experiments spring wheat cv. Solo was grown in hydroculture under greenhouse conditions. The influence of cytokinin applications during grain filling period (Cy: 0 – 100 μg BA/l nutrient solition) combined with different nitrogen supply (N: 0, 0.25, 0.50 and 4.0/1.3 mMol/l) was studied in regard to the development of flag leaves and grains. As to flag leaf, only N was capable to increase specific fresh and dry matter and delay the decrease during development. Similar changes in the chlorophyll content, photosynthesis and N-content of leaves and grains, resp., could be induced by either N or Cy. Grain growth and grain N-content was favoured by N, with the first effect becoming visible early and the second late in the grain filling period. At maturity Cy gave the same effects, but time course was slightly modified. At high doses of N (4.0/1.3 mMol/l) Cy-applications reduced chlorophyll content, photosynthesis and N-content of leaves and grains. This gave rise to the conclusion that cytokinins limit the corresponding physiological processes only if nitrogen nutrition is low.     

Phosphatverarmung des wurzelnahen Bodens und Phosphataufnahme von Mais und Raps

Phosphate depletion at the soil — root interface and the phosphate uptake of maize and rape Maize and rape plants were grown in flat containers in a ³3P-labelled sandy soil and the distribution of soil phosphate near roots was determined by using densitometric scans of autoradiographs. The concentration of isotopically exchangeable phosphate at the root surface decreased within a few days by 42 per cent with rape and by 50–65 per cent with maize. Initially the width of the depletion zone is very small. Within six days the depletion zone extended to the final distance from the surface of the root cylinders of about 2 mm for maize and 2.6 mm for rape. The soil within the range of the mean length of root hairs (0.7 mm for maize and 1.3 mm for rape) is almost equally depleted. This indicates that root hairs are very important for P-uptake from soil. This is further supported by higher P-uptake rates per cm root length of rape than of maize. The P-concentration of the soil solution was estimated by means of the phosphate desorption curve. Within the root hair cylinder the P-concentration of the soil solution decreased from 0.8 to 0.03 mg P/l. Changes of the P-depletion profile with time were used to calculate P-uptake rates for roots of different age. The results indicate that for the first 3–5 days P-uptake rates remained near maximum, even though the P-concentration of the soil solution at the root surface had strongly decreased within two days. Phosphate uptake rates per cm root length did not decrease unless the whole root hair cylinder had been depleted.     

Einfluß von N-Lignin auf Wachstum und N-Stoffwechsel von Weizen-Zellsuspensionskulturen

The effects of N-Lignin on growth and N-metabolism in wheat cells in suspension cultures N-Lignin is an organic N-fertilizer which is synthesized from waste liquors of the pulp industry by oxydative ammonisation. Nearly 40% of its N-content is available as ammonium, the rest is linked in organic compounds. Water-soluble fractions of N-Lignin were added to the nutrient solutions of wheat cells in suspension cultures in order to study the effects on growth and N-metabolism. The experiments show that N-Lignin is a suitable nitrogen source for growing wheat cells. The best growth was achieved when 50% of the total nitrogen content of the medium were added as N-Lignin nitrogen. This mixture of N-Lignin and nitrate was even superior to the standard B-5-medium with respect to the final dry weight. However, higher concentrations of N-Lignin inhibited cell growth. The effect of N-Lignin on cell growth is not only influenced by ammonia. If wheat cells were grown on media with ammonium-N as the sole nitrogen source acids of the citrate cycle had to be added to support growth. This was not necessary with N-Lignin. N-Lignin therefore seems to effect the energy metabolism. High amounts of ammonium-N or the reduced N-fractions of N-Lignin respectively resulted in an increase of certain amino acids and especially of the two amides glutamine and asparagine. Furthermore root formation was observed with cells grown in media containing N-Lignin or ammonium-N. The root formation seemed to be correlated with added amounts of reduced nitrogen. Root formation was not observed with cell cultures incubated with N-Lignin solutions which were made free of ammonium-ions with a cation exchanger (Amberlite IR-120) loadad with potassium. This indicates that the differentiation of roots in the normally embryonic cells is due to the ammonium-N content of N-Lignin. A possible correlation between the content of glutamine and asparagine and the formation of roots is discussed.     

Umsetzung von Cyanamid,Harnstoff und Ammonsulfat in Abhängigkeit von Temperatur und Bodenfeuchtigkeit

Transformation of cyanamide, urea and ammonium sulfate as influenced by temperature and moisture of soil The conversion of cyanamide, urea and ammonium sulfate solutions to nitrate was investigated in a sandy silt loam (pH 6.2) in relation to temperature and soil moisture conditions. 1. Cyanamide was transformed to urea within 1–5 days. Increasing temperature (2°–100°C) accelerated the breakdown, whereas high moisture conditions (120 % of total water capacity) decreased transformation. 2. The hydrolysis of urea to ammonia took place within 5–10 days even at 2°C regardless of whether cyanamide or urea was added. Low soil moisture (40 % of total water capacity) and high temperature (up to 50°) accelerated the breakdown. 3. Following urea application (20 mg N) there was a transient formation of up to five times more nitrite (0.5 mg NO₂-N) as compared with cyanamide or ammonium sulfate treatments. 4. Clear differences were observed in the rates of nitrification. The rate was greater for urea than for cyanamide and ammonium sulfate. The formation of nitrate began at 2°C, with an optimum between 20° and 30°C. Under flooded conditions (120 % of total water capacity) and low temperature the rate of nitrification was slow. At higher temperatures rapid denitrification took place.     

Einfluß von Monoethanolamin auf Ertrag und Wasserausnutzung von Sommergerste

Effect of monoethanolamine on yield and water use efficiency of barley The effect of monoethanolamine (EA) on yield and water use efficiency (WUE) of spring barley plants was tested in pot experiments. The application of EA (8 to 12 mg/pot) increased the grain yield and WUE by about 4 to 15 per cent under stress conditions. In addition, EA improved the utilization of fertilizer nitrogen. The yield-increasing effect of EA was associated with an increase of the number of ear-bearing tillers and an improved root growth. The effects of EA were only significant at α = 0.05.     

Die Chromosomenzahlen von Thymian und Bohnenkraut

Ohne Zusammenfassung     

Vergleich von Nitrat- und Amino-N-Schnelltest zur Charakterisierung des Stickstoff-Versorgungsgrades von Winterweizen

Comparison of the rapid tests for nitrate and amino-N for evaluating the N-status of winter wheat Nitrogen fertilizer trials with winter wheat were conducted in 1985 and 1986 to compare the efficacy of the rapid test for nitrate (in the stem base) and a newly developed rapid test for amino-N (in fully expanded green leaves) for evaluating the N-status of plants. In addition, the influence of weather conditions on the results given by both tests when using ammonium nitrate (NH₄NO₃ + CaCO₃) (AN) and urea-ammonium nitrate solution (UAN), was evaluated to determine wether the rapid test for amino-N gives more accurate information on the N-status of winter wheat than the rapid test for nitrate. The results show that the rapid test for nitrate is suitable to characterize the N-status of winter wheat when nitrogen is predominantly taken up by roots as nitrate. This is normaly the case when plants are fertilized with the salt form of nitrogen, als well as with liquid fertilizer, such as UAN applied through tubes in the soil, as for fertilization of winter wheat at later growing stages. However, during dry weather (1986 field trial) UAN application on leaves at shooting and ear emergence can result in high nitrogen uptake by leaves, causing an underestimation of plant N-status by the rapid test for nitrate, and thus, subsequent excess N-fertilizer application may be recommended (order of magnitude: 20 kg N/ha). Under these conditions the rapid test for amino-N in leaves (pressed sap) is a more accurate test for estimation of plant N-status because it determines glutamine and amino acids, the most important storage forms of reduced nitrogen in plants. When UAN fertilizer on leaves is washed off by rain (1985 field trial), crop N-fertilizer requirements predicted by both tests are comparable. If storage of nitrate in the stem base occurs, due, for example to low radiation intensity during spring (lower nitrate reduction), with the rapid test for amino-N an underestimation of plant N-status can be obtained.     

Aufnahme und Verlagerung von Natrium bei zwei Sorten von Lolium perenne

Uptake and translocation of sodium in two cultivars of Lolium perenne The uptake and translocation of Na was investigated in two Lolium perenne cultivars (Dolewi and NFG). With increasing Na⁺ concentration in the nutrient solution (0, 1, 2 and 4 mMNa) the Na⁺ uptake per pot increased from 1.4 to 11.9 me/1 Na⁺ for Dolewi and from 1.1 to 6.9 me/l Na⁺ for NFG. The higher Na uptake by Dolewi can only partly be explained by better growth, the higher Na⁺ selectivity playing also an important role. In another experiment plants of both types were grown in solution cultures for 41/2 weeks at 15°C and 25°C, respectively. Hereafter the plants were supplied with 1.25 mM ²⁴NaCl for six hours under equal conditions. Again the higher Na uptake and also a higher Na translocation (of about 20%) was found in Dolewi, whereas only 10% of the ²⁴Na uptake had been translocated by NFG. When plants were grown in a nutrient solution with a lower temperature (at 15°C) the root lipids showed a higher linolenic acid and oleic acid content than the plants grown in a medium at 25°C. At the same time the 24Na uptake was higher in the plants grown at the lower temperature, yet the relationship between root lipids and Na uptake still remains to be elucidated.     

Einfluß von konstantem und abnehmendem Nährstoffangebot auf Aufnahme und Verteilung von K,Ca und Mg bei Sonnenblumen

Influence on the uptake of K, Ca and Mg in sunflowers with a constant and a diminishing supply of nutrients. . In a model-test with sunflowers it was investigated how the K-, Ca- and Mg-content in the plants is reacting when (a) a nutrient solution maintained constantly at the same level is given as in a ?good soil”? with a constant supply of nutrients, compared to (b) a solution with diminishing as in a highly fertilized soil but which hardly supplies nutrients itself. It was shown that, if the offer of the nutrient was constant, the cation content in the leaves could be maintained at the same level (the relation of cations is also maintained at the same time). Contrary to this with a diminishing nutrient solution due to removal of nutrients out of the solution without replenishing nutrients and the differentiated nutrient translocation the result was a lesser and lesser content of the nutrients inside the plant and more evident changes in the relation of cations, even before the insufficient supply was noted in a decreasing crop. Only in the leaves the relation of cations was nearly constant (K:Ca:Mg = 6:3:1). From these results it can be concluded that, through a high single supply of nutrients the effect of a constant flow of nutrients from the soil to the plant concerning the mineral contents of the plant cannot be compensated.     

Heterosiseffekt und Pigmentgehalt am Beispiel von zwei Hybridtomatensorten und ihren Eltern

Zusammenfassung Der Pigmentgehalt von zwei Hybridtomatensorten Nr. 10 × Bison und Sarja × Komet und von deren Eltern Nr. 10, Bison, Sarja und Komet wurde bestimmt. Die Blätter der Bastarde Nr. 10 × Bison sowie Sarja × Komet führten höhere Chlorophyll a-, Chlorophyll b-, Carotin- und Xanthophyllmengen als diejenigen ihrer Ausgangsformen. Der Phaeophytingehalt lag bei den Hybridformen immer niedriger (zum Teil viel niedriger) als bei den Eltern.

---

Summary The pigmentation of two hybrid varieties fromLycopersicon esculentum Nr. 10 × Bison and Sarja × Komet and their parents Nr. 10, Bison, Sarja and Komet, was determined. The leaves from the bastards Nr. 10 × Bison and Sarja × Komet had more Chlorophyll a, Chlorophyll b, Carotin and Xanthophyll than those from their parents. The content of Phaeophytin was in the hybridforms lower (partly much lower) than in the parents.

---

, 10 × × , . a, b, , . ( ) .

---

---

Zentralwissenschaftliches Institut für Gemüsekulturen Mariza bei Plovdiv (Bulgarien). Die Arbeit wurde während eines Gastaufenthaltes am Institut für Pflanzenzüchtung der DAL Quedlinburg und am Institut für Kulturpflanzenforschung der DAW zu Berlin in Gatersleben durchgeführt.     

Methoxylgehalt,PSR und Farbreaktionen bei Wurzel- und Strohlignin von Triticum

Methoxyl content, PSR and color reactions on root and straw lignin The wet chemical measured content of methoxyl groups is in lignin from up to 13 cm long roots and straw with ～ 11,5 % nearly indentical. Lignin in roots contains more keto groups. This was proved by psr-spectroscopy (δ = 8 ppm) and by various color reaction with o–dianisidine/HCl, diphenylamine, acridine, barbituric acid, p-anisidinhydrochloride, sulfanilic acid and aniline. Root lignin has also more benzolic protons (δ = 5,35 – 5,45 ppm) and by far higher part of highly shielded aliphatic protons (δ = 1,33 ppm). The last diminished to a large extend after having react with diazomethane. From this informations could even be concluded that lignin in roots has more methylable structures. Against that protons in the side arms are to find more in the lignin of straw.     

Einfluß von Ammonium- und Nitratstickstoff auf die Entwicklung von Buchenjungpflanzen

Influence of ammonium and nitrate nitrogen on the growth of young beech plants Young beech plants were grown in aerated nutrient solutions with NH₄ or NO₃ nitrogen for a period of 12 weeks. pH-changes caused by the source of nitrogen were corrected every second day. Absorption of NH₄-N was higher than of NO₃-N. NH₄-N was superior for shoot growth and development of lateral roots, NO₃-N for growth of the main root. Nutrient solution containing both sources of nitrogen was the most favorable.     

Verteilung von Stickstoff auf Sproß und Wurzel bei jungen Bohnenpflanzen nach der Aufnahme von NO und NH

Translocation of nitrogen to the shoot of young bean plants after uptake of NO and NH by the root Phaseolus vulgaris plants (var. nana, cv. Saxa) at the primary leaf stage (without nodules) were fed during 6 hours with ¹⁵NO and ¹⁵NH, respectively. 24 hours after the absorption period more ₁₅N from the absorbed NO was translocated from the root to the shoot. The presence of NH in the nutrient solution enhanced the translocation of ¹⁵NON, probably by an inhibition of nitrate reductase. NH_4-⁺¹⁵N is mainly retained in the root by a high incorporation into the root protein. It can be concluded that nitrogen from newly absorbed NO is not retained and used for protein synthesis in the root according to the root's potential to synthesize protein. Nitrate reduction in the root is considered to be the limiting factor. This is supported by the fact that withdrawal of NO in the nutrient solution prior to the ¹⁵N-experiment increased NOtranslocation to the shoot as a consequence of a lowered level of nitrate reductase. In an experiment with ¹⁴NOsupply to the roots and ¹⁵NOapplication to the primary leaves (infiltration method) a considerable amount of ¹⁵N was translocated from the leaves to the roots. This indicates that an insufficient NOreduction in the root can be substituted by a retranslocation of reduced N-compounds from leaves to the roots. The proportion of NO reduced in the root influences also the pattern of primary distribution of nitrogen in the shoot of plants at the 4 leaf stage. At a concentration of 0,2 meq/l NO in the nutrient solution as compared to 20 meq/l NO during 10 hours a relative higher amount of ₁₅N was transported from the root to the younger, growing leaves i.e. via the phloem to metabolic sinks.